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Physiological Fluid Mechanics

Artificial Heart

Presented by: Benedict LeungDean Zhao

11/01/2004

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The Heart

Its just a pumpA very complex oneBut, still a pumpSmall cone shapedAbout 12 cm long and 9 cm wideWeight: Female 250g, Male 300gLocated near midline of thoracic cavityAdult pumps about 70 ml/beat, 75 beats/min,

5.25 L/min (at rest)

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Pulmonary valve

Right atrium

Mitral valve

Left Ventricle

Right ventricle

Tricuspid valve

Left atrium

Structures

Aortic valve

• One way transport of blood

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Circulation

Two of the heart valves control the flow of blood from the upper chambers to the low chambersTwo other valves control the flow of blood from the ventricles to the lungs and the body.Pumping action

Atria first, ~0.1s delay then ventriclesLeft ventricle muscle is thicker than other chambers

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Types of Disease of the heart

Valve DisorderStenosis – valve cannot open fullyIncompetence – valve cannot close completelyCauses backflow - may not pose a serious threat if volume is smallCertain infectious diseases can damage the hearteg Rheumatic Fever

Arrhythmias• Reduce ability for the heart to conduct electrical signals• Flutter – rapid atrial contractions (240-360 beats/min)• Fibrillation – asynchrony of contractions

very dangerous especially ventricular fibrillation

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Coronary Artery Disease (CAD)

Number one killer in North AmericaThickening of coronary artery walls reduce blood flow to the myocardiumMay lead to total obstruction

Myocardial Ischemia (reduced blood flow to the myocardium)

Angina pectoris – severe pain in chest neck, chin, or down left arm to elbow

Myocardial Infarction (heart attack)Death of an area of tissue

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Methods of CorrectionTreatment of CAD

Coronary artery bypass grafting

Surgical procedure in which a blood vessel from another part of the body is grafted to a coronary artery to bypass a blockage

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Percutaneous transluminal coronary angioplasty

Balloon catheter is inserted into artery of arm or leg, guided to narrowed artery. Balloon inflates, it stretches arterial wall and squashes the plaque. Therefore widens the arteryStent maybe put in place to prevent renarrowing

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Help for Failing HeartsCardiac assist device

Intra-aortic balloon pump – a balloon pump is inserted in thoracic aorta creating counterpulsation with respect to Left ventricular pulse to make coronary blood flow and reduce left ventricle load

Cardiomyoplasty – skeletal muscle wrap around heart, peacemaker elicit contraction, contract 10-20 times, insynchrony with some heartbeat

Skeletal muscle assist device – similar to cardiomyoplasty, placed between heart and aorta. act as booster heart

Left ventricular assist device (LVAD) – total portable. Implanted to weakened left ventricle, pumps blood into aorta.

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Jarvik 2000 Flowmaker (LVAD)

FDA approved bridge-to-transplant use,Longest patient support – more than 4 yearsSize of C type batterySpinning rotor to propel bloodNatural heart continues to contract; patients retain a pulse.

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Jarvik 2000 cont’d

Small size allows implantation inside the left ventricle of the heart. "booster" pumpOutput of device is controlled manually (8k-12k rev/min)Not a single mechanical error with more than 100 patientsWire out of body lead to inconvenience, open to infection

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Artificial Heart

History (Evolution of artificial heart)In the early 1800s, an awareness of potential ventricular failure stimulated interest in artificial heart replacement. In 1937 the first total artificial heart (TAH) was implanted into the chest of a dog by Russian physicians.

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Evolution of Artificial Heart (cont’d)

1950s and 1960s

the heart-lung machine, prosthetic materials to replace damaged arteries and veins and to close holes between heart chambers, replacement valves, implantable pacemakers, the intra-aortic balloon pump (IABP)

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Evolution of Artificial Heart (cont’d)

1970s and 1980s

the IABP gains wide acceptance as a temporary cardiac assist system.

external and implantable ventricular assist devices enter clinical trials.

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Evolution of Artificial Heart (cont’d)

1990s

ABIOMED’s BVS 5000™ Bi-ventricular Support System, approved by the U.S. Food and Drug Administration for support ofpatients with failing but potentially recoverable hearts.

external and implantable left ventricular assist devices, approved for temporary support as a bridge-to-transplantation.

Before ABIOMED’s developmental work on a fully Implantable Replacement Heart, experimental artificial heart technology relied on large external power and control units.

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Milestones in artificial-heart technology

Designed by Drs. Willem Kolff and Tetsuzo Akutsu in 1958, this polyvinyl chloride device sustained a dog for 90 minutes.

Dr. Willem Kolffand his team developed this silicone rubber heart for a calf in 1965.

This 1969 heart, designed by Dr. Domingo Liotta, was the first to be implanted in a human being as a bridge to transplant by Dr. Denton A. Cooley. The patient survived for almost three days with the artificial heart and 36 hours more with a

transplanted heart.

The artificial heart developed by a team led by Drs. Willem Kolff, Donald Olsen, and Robert Jarvik, the Jarvik-7, was the first to be implanted in a human as destination therapy in 1982, by Dr. William

DeVries.

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Jarvik-7 Total Artificial Heart

Named for its designer, Dr. Robert JarvikBegan in 1982 First patient survived with the Jarvik-7 for 112 days Five more implantations of the Jarvik-7 were performed through 1985. The longest survivor was William Schroeder, who was supported by the Jarvik-7 for 620 days

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Design of the Jarvik-7

two heart pumps and a power console heart pumps are small enough to fill the void left behind during ventricle extraction receive power through a large external console that pushes air through percutaneous tubing The drive-lines out of the ventricular air chambers are made of reinforced polyurethane tubing

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Design of the Jarvik-7 (cont’d)

Seven feet away from the patient rests a heavy power console from which doctors adjust the patient’s heart rate and the cardiac output

Is there a better solution?

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Abiocor Total Artificial Heart

a permanent artificial heart that is completely self-contained within the body began in the early 1980s, around the time of the Jarvik-7July 2001 Abiocor artificial heart received FDA approval for clinical testing The first patient implanted with the Abiocor, Robert Tools, lived for nearly five months

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Improvements (compared to Jarvik-7)

better surface materials to reduce blood clotting a newly engineered power system that does not require skin-piercing electrical cords a small computer secured in the abdomen of a patient automatically adjusts the output of the pump Patients were able to stand up and walk around (Ex. Showering)operate so quietly that a “stethoscope is needed to listen to the heart sounds”

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Design of the Abiocor

Three subsystems implanted under the skin make up the design of the Abiocor

the heart pump, a computerized pump controller, and a power source

Surgeons implant the heart pump in the area from where the ventricles are removed Channels that connect naturally to the ventricles are then sewn into artificial cuffs that snap on to the heartTwo independent hydraulic motors lie inside the heart

One motor maintains the pumping function to each ventricle while the other motor operates the motion of the four heart valves

The pumping motion operates through hydraulics by an oscillating pusher plate that squeezes sacs which alternatively expel blood to the lungs and the body

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Design of AbioCor (cont’d)

Material of AbioCormade of titanium, plastic and AngioflexAbout two pounds

Power supply of AbioCorWireless power transfer systemExternal battery supplies 4-5 hours powerInternal battery supplies 30-40 minutes power

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Cross-sectional view of AbioCor

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Animation

Watch this animation to get an idea of how the AbioCor™ heart works. You will see the hydraulic pump shuttling fluid back and forth across an artificial septum. The pressure this movement generates pushes blood out of one of the ventricles, while drawing blood into the other. The blood heads out to either the lungs or the rest of the body

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Recap of AbioCor

Is capable of producing more than two gallons of blood every minute (normal heart is 1.3 gallons per minute)

a small computer secured in the abdomen of a patient automatically adjusts the output of the pump.

implant an electric coil in the abdomen area to allow for energy transfer across the skin.

One significant advantage to the Abiocor is the smooth surface of the blood sacs.

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Testing Animation

To test the reliability of the AbioCor™ system, every valve, tube, hydraulic membrane, and covering was subjected to rigorous testing in tanks of salt water. Salt water mimics the corrosive action of blood and other bodily fluids that the artificial heart will encounter once inside your body. To get FDA approval, the components of the AbioCor™ heart had to beat 200 million times-enough to sustain life for about five years

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People who qualified for Abiocortransplantation

Have end-stage heart failure Have a life-expectancy of less than 30 days Is not a candidate for a natural heart transplant Have no other viable treatment option

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Other Total Artificial Heart

Phoenix-7 TAHDeveloped and constructed in Asia, is a success, and it is suitable for patients as a bridge to HTx

Liotta TAHair-driven (pneumatic), double-ventricle pump In 1969, it supported a patient for nearly three days as a bridge to HTx

CardioWest TAHpatients who have irreversible biventricular failure and are candidates for cardiac transplantation

Summary of the above TAHAll are pneumatically-drivenAll are bridges to HTx, not totally self-contained TAH.

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Refereneces

http://www.engr.utexas.edu/uer/artheart/body.htmhttp://www.texasheartinstitute.org/abiocor.htmlhttp://science.howstuffworks.com/artificial-heart.htmhttp://www.mos.org/cst/article/3737/9.htmlhttp://www.syncardia.com/FDA_101804.phphttp://www.jarvikheart.comhttp://www.medicinenet.com/coronary_artery_bypass_graft/page2.htmhttp://www.torrancememorial.org/carptca.htmPrinciples of Anatomy & PhysiologyTenth Edition. Pages 660-687 Tortora Grabowski

http://www.engr.utexas.edu/uer/artheart/body.htmhttp://www.engr.utexas.edu/uer/artheart/body.htmhttp://www.texasheartinstitute.org/abiocor.htmlhttp://www.texasheartinstitute.org/abiocor.htmlhttp://science.howstuffworks.com/artificial-heart.htmhttp://science.howstuffworks.com/artificial-heart.htmhttp://www.mos.org/cst/article/3737/9.htmlhttp://www.syncardia.com/FDA_101804.phphttp://www.jarvikheart.com/http://www.medicinenet.com/coronary_artery_bypass_graft/page2.htm

Physiological Fluid MechanicsThe HeartCirculationTypes of Disease of the heartMethods of CorrectionTreatment of CADHelp for Failing HeartsCardiac assist deviceJarvik 2000 Flowmaker (LVAD)Jarvik 2000 cont’dArtificial HeartEvolution of Artificial Heart (cont’d)Evolution of Artificial Heart (cont’d)Evolution of Artificial Heart (cont’d)Milestones in artificial-heart technologyJarvik-7 Total Artificial HeartDesign of the Jarvik-7Design of the Jarvik-7 (cont’d)Abiocor Total Artificial HeartImprovements (compared to Jarvik-7)Design of the AbiocorDesign of AbioCor (cont’d)Cross-sectional view of AbioCorAnimationRecap of AbioCorTesting AnimationPeople who qualified for Abiocor transplantationOther Total Artificial HeartRefereneces